it really depends on where you are located. The best place to start is your local herp society. I also watch classified ads for "adoptions". Also some spca's have reptiles from time to time and you can give them your name and number to call you for certain things that you would be interested in. I also run an ad on CL "taking in unwanted reptiles, No questions asked no sob story or caging needed" I get them healthy and use the ones with good dispositions in my reptile demonstrations until I find a suitable home. Some times i'll donate them to my local herp society to auction off so they can use the money for supplies to continue operations and rescueing.
I try that but sometimes I just get impatient or one thats not perfect speaks to me. lol